The present invention provides a light-emitting device with a reflection layer and the structure of the reflection layer. The reflection layer comprises a variety of dielectric materials. The reflection layer includes a plurality of dielectric layers. The materials of the plurality of dielectric layers have two or more types with two or more thicknesses, except for the combination of two material types and two thicknesses, for forming the reflection layer with a variety of structures. The reflection layer according to the present invention can be applied to light-emitting diodes of various types to form new light-emitting devices. Owing to its excellent reflectivity, the reflection layer can improve light-emitting efficiency of the light-emitting devices.